


The Cave

by TheFourDoctors



Category: Shingeki no Kyojin | Attack on Titan
Genre: Anal Fingering, Anal Sex, Bottom Levi (Shingeki no Kyojin), Kissing, M/M, Mating Cycles/In Heat, Modern Era, Top Eren Yeager
Language: English
Status: Completed
Published: 2018-11-11
Updated: 2018-11-11
Packaged: 2019-08-22 08:57:15
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,226
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16594826
Author URL: https://archiveofourown.org/users/TheFourDoctors/pseuds/TheFourDoctors
Summary: While making his way to his usual spot, Eren stumbles upon a merman, and things escalate from there.





	The Cave

Eren had seen strange sights, yes, but this had to be the strangest sight he had ever seen.

The man had just been exploring a small cave that met the sea at his local beach. It was secluded, far enough from the main area of the beach to be quiet, and it was a place he came to often for some peace.

He never expected anyone to be there, so it came as a surprise when someone was there, a mermaid nontheless.

Eren almost pinched himself, full of disbelief. There was no way it was real, and yet...proof laid right infront of him.

He had never believed stories he heard, people saying they saw a mermaid or something. It just didn't seem possible, but now he was starting to reconsider his thoughts.

Stepping forth, he carefully maneuvered on the slippery rocks, wet with the tide and covered in moss. The creature didn't seem to be moving, and he felt dread, hoping it wasn't dead.

As he approached, Eren was able to make out it's features. The creature was not female as he had thought. 'So..a merman?' He seemed to be breathing, which was a plus.

The merman had a toned yet lean torso, strong, filled out arms, and even abs to top it off. In the light of afternoon, he could spot fin-like ears, webbed between three spikes of cartilage. Three gills adorned his neck, pale skin almost glowing in the sun.

But what facisnated him the most was the deep sea blue tail, adorned with light blue fins and speckles of teal and green. It wasn't scaled like many would believe. The tail was more like a dolphin's, but longer and powerful.

Despite being skin, it seemed tough and durable, with a few scars here and there. In fact, the merman's whole body had scars, suggesting a long life of fighting and survival in the sea.

Entranced, he stepped closer, foot splashing in a small puddle of water and effectively waking up the merman.

Piercing silver/blue eyes caught his own and stared into his soul, thin eyebrows expressing confusion, wet raven black strands clinging to his skin. Surprisingly, he had an undercut, which one would not expect at all from a sea creature. Although, he supposed they had a lot more intelligence than some gave them credit for.

Those eyes blinked owlishly at him, revealing a second set of eyelids beneath the first. It was expected though, many animals had more than one, and cats even had three.

As Eren knelt down beside the merman, he expected to be attacked, maybe even torn apart by those meanacing claws, but the creature didn't even seem antagonized or scared, just surprised. He even tilted his head a little, seeming...curious.

Eren looked down and inspected him. The merman didn't seem injured, so that couldn't be why he was there. Was he washed up? It didn't seem so. The rocks were too high to wash up an animal, so he likely climbed up on his own. Was he escaping from something, or did he just want somewhere to sleep? Everything was a mystery at this point.

He did note, however, that the merman was panting slightly, skin flushed with red in some areas, and the base where his tail met skin was a darker blue than the rest. Did this mean anything? He wasn't an expert on merman by any means, and his major in marine biology did nothing to help here.

"Why are you here..?" He wondered to himself, but the merman seemingly caught his words and whistled quietly, possibly trying to decipher English. He didn't expect him to be able to speak words, his vocal chords had to be vastly different if he wanted to communicate with others under water. Still, it was fascinating how he tried to communicate nonetheless. 

His tail splashed slightly in the water, arms hoisting himself up and displaying incredible upper body strength. He was now sitting upright and seemed to be shorter than Eren.

The brunette supposed he should try asking for a name, but again, he probably couldn't speak his language, so he had to give him one. Observing the strong yet surprisingly handsome features, he settled on one fitting name. "Levi? I'm Eren."

The newly named Levi trilled quietly, webbed and clawed hands gently tracing the tanned skin of his cheeks in wonder. Internally, the human questioned if Levi had ever seen one of them before, but he seemed totally unconcerned at his lack of tail so Eren supposed he had.

The surprisingly gentle touch slid up to his hair, carding through silky chestnut strands and then down to the nape of his neck. Despite being curious as to what exactly the merman was doing, he didn't push him off, instead letting him explore.

Eren watched with silent awe as Levi's tail splashed more insistently in a pool of water, pulling away to dip into it fully and practically tugging on Eren's arm, trying to get him to come with.

Although he was reluctant to get his clothes wet, Eren supposed it couldn't hurt, so he slipped into the pool with the merman, who seemed happy that he complied.

The water only went up to his waist when sitting on the deepest end, so he supposed it was alright.

Levi whistled and slide up right next to Eren, completely unconcerned about personal space and seemingly more content with flopping his tail over his lap.

Although, Eren was too facisnated to mind, his inner marine biologist screaming at how amazing this was and how he got to observe a merman up close.

His hand had a mind of it's own, trailing down to slide over the smooth tail. It wasn't slimey, it was more oily like many sea mammals and fish. His pelvic fins were folded and looked much like his ear fins.

While he was busy petting and exploring the tail, the merman leant close to his neck and inhaled silently, taking in the scent of pine and something else he couldnt decipher. It was probably those things humans sprayed on themselves to smell better, but to Levi, it was incredibly enticing.

He had come to the beach because he was in heat. Mermaids usually sought out humans to mate with since mermen were incredibly rare, and those base instincts carried onto mermen too. They didnt seek out mermaids, instead doing what the females did and finding a suitable human for their needs.

The beach was where a lot of humans could be found, but he wasn't dumb enough to go out in plain sight. Levi knew the risks, he knew some humans could be cruel, just like how some mermaids could be cruel, so he found this cave and waited. His patience brought this human to him. He didn't care for gender.

The human was obviously male, and Levi guessed he was named Eren from what he said earlier, despite not being able to understand much else he had said.

Trilling, he pressed closer, sliding his hands down and then up under the material of Eren's shirt, effectively surprising the human. He would have been amused, but was more enticed by the strong skin he found, eyelashes fluttering slightly and another wave of arousal crashing over him.

He wanted the human so badly.

Eren gasped quietly at the surprisingly warm hands currently touching him, the merman getting more and more frisky as time passed, and it finally clicked into place.

He remembered old stories about mermaids seeking out humans as mates, and it finally made sense. Levi clearly wanted him in that way, and was waiting for Eren to make a move. Clearly, the merman knew about consent, and he supposed it wouldn't hurt to give it a try. Besides, the touches were doing more to his body than he realised they could.

Swallowing dryly, he set his hands upon Levi's waist, trailing one lower until they settled on a smooth, very dark blue area of skin, where his fingers caught on a slit in the skin. Curiously, he slipped them in, sucking in a breath at the sheer tightness and warmth of it. It was fleshy and wet, and Eren felt a spark of arousal shoot through him at the thought of being buried inside of that tightness.

Levi seemed to be appreciating it too, mewling and panting into his ear, clutching desperately at his waist. Eren felt another wave of heat in his belly, hips bucking up against that strong tail. He swallowed again, twisting his fingers to press even deeper. 

Something warm and hard pulsated above his hand, and a large, flesh mass grew bigger and bigger, resembing that of a penis. It looked achingly hard, dripping with precum and twitching with every thrust of Eren's fingers.

The human was beyond aroused at this point, panting along with Levi and twisting his fingers curiously, pressing up against the smooth wall of flesh.

The merman jumped and keened loudly, the brunette's eyes widening in surprise. He never expected merman would have prostates, but it made sense given the fact that they had genitalia like human males did.

Shifting, he pressed up again, wide eyes watching as Levi thrashed around, face screwed up in pleasure and shameless cries echoing in the cave. Every hard rub against the little bundle of nerves had the merman crying out, claws practically tearing easily through his shirt to clutch at his back.

Eren swallowed, not at all caring when Levi tore the shirt off. He desperately wanted to fuck him, and the merman was on the same page, pulling him insistently to a shallow end of the pool to lay down and expose himself.

The human wasted no time in tugging off his shorts, throwing them aside quickly. His dick throbbed in anticipation, his legs settling themselves on either side of Levi's strong tail. Eren guided himself to the slit, slowly and carefully slipping inside.

"Fuck!" It was so unbelievably warm and tight, the strong muscles inside his tail clenching mercilessly around the intrusion. Levi tossed his head back, jaw slack and an almost human sounding moan dropping from his throat. Eren would have been more surpised, but he was more concerned with how good it felt to be buried inside that heat.

Levi's hands reached down to grip at his hips, impatiently bucking his own up. Eren took the hint, quickly thrusting his hips forward and back again and again, animalistic groans falling from his throat.

Another deep, rumbling moan fell from the merman's lips, eyes shut tightly in pleasure, eyebrows upturnt and face flushed a deep crimson. If he had legs, he would have been wrapping them around Eren's waist by now. Instead, his tail curled around one of the human's legs, hands clutching and digging into the skin of his back.

Levi had no idea it would feel this good. For years, he fought away the instinct to mate, ignoring his body's desires and instead entirely focused on survival. He'd gotten himself off a couple times when the need became too much, but he never imagined how incredible sex would be.

He suddenly didn't want to let this human go, arms pulling Eren down to lick and bite at his neck. Levi's body was pooling with heat and pleasure at every push of the brunette's hips and every slick slide inside of him.

The human panted, hiding his face in Levi's neck, oh so very close to that small bud that would mark a merman as claimed. He wished so desperately to be able to speak Eren's language, to communicate and beg him to claim him.

All it took was one brutal thrust against his prostate that had the merman coming undone, sounds he once held back spilling forth in a staccato of mewls and moans, Levi baring his neck to the side in a silent plea, the human thrusting mercilessly against his prostate.

Eren groaned loudly, sucking his neck lower and lower, teeth scraping the small bud of skin. Something was calling to him, a deep instinct buried inside Eren telling him to bite down, so he did.

Instantly, a pleasant warmth flooded their bodies, tingling beneath the skin. Levi's eyes rolled back at the pleasure, waves upon waves of cum painting their chests white and practically squeezing Eren inside of him, causing the human to cry out and cum inside of him.

The sticky warmth filled him up to the brim, and he felt Eren collapse ontop of him. The only sounds now filling the quiet cave were pants and soft whines.

Eren's mind was spinning, clouded with bliss, body warm with something he couldn't describe. All he knew was that he wanted to kiss Levi. Something deep inside was telling him to.

He pushed himself up on to his elbows, leaning down slowly. Levi blinked hazily and met him halfway, the two lazily kissing. It felt incredible. Eren was so distracted, he missed the warm orange glow that now surrounded the merman.

Eventually, he pulled away, eyes fluttering open to take in...human ears? Turquoise eyes blinked slightly in confusion until he felt two strong appendages wrap around his waist. Realisation dawned on him. 

Levi licked his lips and teasingly bit at the brunette's ear, whispering, "you up for another round, kid?"

**Author's Note:**

> Hope y'all sinners enjoyed this as much as I enjoyed writing it! I'm considering maybe continuing this as a series, but as of right now, it's complete.


End file.
